| 摘要 |
PURPOSE:To attain excellent operation by providing a converging grating coupler in separating the coupler into two, for guided light output and reflected light input. CONSTITUTION:A guided diverging light 8 stimulated by a light source 7 is diffracted by the transmitted light output converging grating coupler 3 to go to an output light 9 and collected on a signal face having pits 12 on an optical disk 11. A light 10 reflected on the signal face is inputted to the reflected light inputting converging grating couplers 41, 42 of the same shape and goes to converging guided lights 81', 82' and coupled with 2 sets of 2-split photodetectors 51, 51' and 51, 52'. In operating output electric signals from the photodetectors 51, 51' and 52, 52', a reproducing signal, a focus error signal and a tracking error signal are detected. Thus, the excellent and stable operation is attained. |
